[1] Nine manufacturers responded with designs,[2] and while some gained contracts for single prototypes, such were the potential rewards that others, like Westland, built aircraft as private ventures.
Contenders were the Armstrong Whitworth A.W.19, Blackburn B-7, Bristol 120, Fairey G.4/31, Handley Page HP.47, Hawker P.V.4, Parnall G.4/31, Vickers Type 253 and the Westland PV.7.
The Ministry expressed a preference for an air-cooled engine[4] and all manufacturers apart from Armstrong-Whitworth and Blackburn chose the nine-cylinder Bristol Pegasus radial.
Leading-edge Handley Page slats were fitted outboard, and the inboard trailing edges carried 4 ft 9 in (1.45 m) span split flaps that opened symmetrically above and below the wing to act as dive brakes.
The second crew member's large cockpit was just behind the trailing edge, enclosed in a multi-piece, segmented glazed cover that could be folded away forward when gunnery using the Scarff ring mounted Lewis machine gun was necessary.
On 25 August,[6] at the request of the Air Ministry Penrose flew the aircraft again, making tests of its behaviour with the centre of gravity far aft.
Penrose was lucky to escape by parachute, as the upper hatch had jammed and he had to squeeze out of a small side window, becoming the first British pilot to bale out of an aircraft with an enclosed cockpit.
[7] It was the end of Westland's G.4/31 hopes, though; the Air Ministry would not pay for the loss of an aircraft flown by a civilian, and the company could not afford to build a replacement.